From: tamouse mailing lists <tamouse.lists@...>
Date: 2013-01-08T21:12:22+09:00
Subject: Re: ruby 1.9.3p362 ranges as conditions bug?

On Mon, Jan 7, 2013 at 12:01 AM, Matma Rex <matma.rex@gmail.com> wrote:
> On Mon, 07 Jan 2013 05:26:43 +0100, tamouse mailing lists
> <tamouse.lists@gmail.com> wrote:
>
>> On Sun, Jan 6, 2013 at 9:09 PM, windwiny <windwiny.ubt@gmail.com> wrote:
>>>
>>> vs = (1..9).to_a
>>> => [1, 2, 3, 4, 5, 6, 7, 8, 9]
>>>
>>> v1 = vs.select { |n| if n==3..n==6 then 1 end }
>>
>>
>> What do you expect n==3..n==6 to do? That evaluates to a range of
>> booleans, depending on the value of n:
>
>
> These are so-called flip-flops, and a valid though obscure feature of Ruby.
> Here's a nicer test case:
>
> irb(main):001:0> (1..100).each do |i|
> irb(main):002:1*   puts i if i==42..i==45
> irb(main):003:1> end
> 42
> 43
> 44
> 45
>

I really do not understand how this works. I can see what it produces, but why?